Millions of people suffer and die from various forms of cardiovascular disease, including coronary artery disease and peripheral vascular disease (also known as peripheral arterial disease). Coronary artery disease and peripheral vascular disease can arise due to the narrowing of the arteries by atherosclerosis (also called arteriosclerosis). Atherosclerosis is a progressive disease and occurs when fat, cholesterol, and other substances build up on the walls of arteries and form fleshy or hard/calcified structures called plaques/lesions. As plaque forms within the native arterial wall, the artery may narrow and become less flexible, which may make it more difficult for blood to flow therethrough. In the peripheral arteries, the plaque is typically not localized, but can extend in length along the axis of the artery for as much as 10 mm or more (in some instance up to 400 mm or more).
Coronary artery disease develops when the coronary arteries become damaged or diseased, generally as a result of plaque deposits within the arteries. Such plaque deposits result in narrowing of the arteries, decrease in blood flow to the heart, and eventually cause chest pain (angina), shortness of breath, or other coronary artery disease signs and symptoms. A complete blockage can cause a heart attack and death. Peripheral vascular disease develops when narrowed arteries reduce blood flow to parts of the body outside of the hearth and brain, such as the limbs. Upon developing peripheral vasculature disease, a person's extremities, usually their legs, fail to receive enough blood flow to keep up with demand. Complications of peripheral vasculature disease may include activity-induced claudication sores that do not heal, ulcers, gangrene, tissue loss, or infections in the extremities. In rare cases, if left untreated, amputation may be necessary.
Endovascular clearing procedures to reduce or remove the obstructions from within an artery are known. Vascular specialists can now choose from a variety of endovascular technologies, ranging from traditional approaches, such as percutaneous transluminal balloon angioplasty (PTA) and self-expanding nitinol stents to newer advancements, including atherectomy catheters and drug-eluting balloons and stents. In balloon angioplasty, for example, a physician may advance a collapsed, intravascular balloon catheter into a narrowed artery, and may inflate the balloon to macerate and/or displace plaque against the vessel wall. A successful angioplasty may help reopen the artery and allow for improved blood flow. Often, balloon angioplasty is performed in conjunction with the placement of a stent or scaffold structure within the artery to help minimize re-narrowing of the artery. Balloon angioplasty, however, can stretch the artery and induce scar tissue formation, while the placement of a stent can cut arterial tissue and also induce scar tissue formation. Scar tissue formation may lead to restenosis of the artery. In some instances, balloon angioplasty can also rip the vessel wall.
Atherectomy is another treatment methodology for atherosclerosis. Atherectomy involves the use of an intravascular device to mechanically remove (e.g., debulk) plaque from the wall of the artery, thereby reducing the risk of stretching, cutting, or dissecting the arterial wall and causing tissue damage that leads to restenosis. In some instances, atherectomy may be used to treat restenosis by removing scar tissue.
Current atherectomy treatments suffer from structural and performance limitations. For example, some current atherectomy devices with rotating burrs generally are not configured to capture particles that are released as the burr grinds/sands tissue, which may result in diminished downstream blood flow resulting from particle residue. Additionally, these rotating burrs may cause hemolysis, and are generally limited as an adjunct therapy to angioplasty. Other systems may include expandable cutters with foldable/movable cutting wings and vacuum-driven aspiration supplied via a vacuum pump, which may cause the artery to collapse on to the cutter and perforate the arterial wall. Other atherectomy systems may include a side-window eccentric cutter and distal nosecone which receives material from the cutter. Because the nosecone can only hold a limited volume of plaque, a surgeon may need to repeatedly withdraw the cutter and flush plaque and other material from the nosecone.